1. Field of the Invention
This invention relates to photographic apparatus and more particularly to a latch assembly for a loading door.
2. Description of the Prior Art
Photographic apparatus, for example cameras, are generally provided with a film loading door which is mounted to a camera housing for movement between an open position wherein a film assemblage, e.g., a film cassette containing one or more film units, may be inserted into a film chamber of the camera and a closed position. The door is usually held or maintained in the closed position by a latch assembly comprised of a least two latching members, one of which is mounted on the door for movement therewith while the other latching member is mounted on the main body of the camera. A manually operable latch assembly actuator is provided for moving one of the latching members out of latching engagement with the other member thereby permitting the door to be moved to its open position. It has been found that sometimes the operator of such cameras may attempt to move the door from its closed position to its open position prior to depressing or otherwise actuating the latch assembly actuator. Often, the force applied to the door during such attempt has been great enough to damage the latch assembly and or door.
U.S. Pat. No. 4,000,500 suggests one possible solution to the aforementioned problem. It appears from the penultimate paragraph of the specification of said patent that the latching members are constructed such that when they are in the latched or locked position there is a built-in threshold torque which, if exceeded by an inadvertently applied torque to the door in an attempt to open it without operating the latch assembly release button, will allow the system to become unlatched without failing of any of its parts. It appears from the foregoing and from an inspection of FIG. 4 of said patent that the rotatably mounted latching member on the film loading door is cammed by the stationary latching member in a counterclockwise direction out of latching engagement therewith by such inadvertently applied torque. However, since it appears that the movable latching member of the patent always moves in the same plane during such unlatching, it would also seem to follow that the tolerances of the latching system must be kept within close limits in order for the system to operate as described. In other words the system described in the aforementioned patent is not very forgiving when it comes to deviations in manufacturing tolerances, which deviations, although by themselves may be within their individual limits, may add to a final tolerance deviation which is not economically feasible.